/////////////////////////////////////////////////////////////////////////////
// Original code from libhdfs3. Copyright (c) 2013 - 2014, Pivotal Inc.
// All rights reserved. Author: Zhanwei Wang
/////////////////////////////////////////////////////////////////////////////
//  Modifications by Kumo Inc.
// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//



#pragma once

#include <memory>

#include <string>

namespace Hdfs {
namespace Internal {

class FileSystemInter;

/**
 * A input stream used read data from hdfs.
 */
class InputStreamInter {
public:

    virtual ~InputStreamInter() {
    }

    /**
     * Open a file to read
     * @param fs hdfs file system.
     * @param path the file to be read.
     * @param verifyChecksum verify the checksum.
     */
    virtual void open(std::shared_ptr<FileSystemInter> fs, const char * path,
                      bool verifyChecksum) = 0;

    /**
     * To read data from hdfs.
     * @param buf the buffer used to filled.
     * @param size buffer size.
     * @return return the number of bytes filled in the buffer, it may less than size.
     */
    virtual int32_t read(char * buf, int32_t size) = 0;

    /**
     * To read data from hdfs.
     * @param buf the buffer used to filled.
     * @param size buffer size.
     * @param position the position to seek.
     * @return return the number of bytes filled in the buffer, it may less than size.
     */
    virtual int32_t pread(char * buf, int32_t size, int64_t position) = 0;

    /**
     * To read data from hdfs, block until get the given size of bytes.
     * @param buf the buffer used to filled.
     * @param size the number of bytes to be read.
     */
    virtual void readFully(char * buf, int64_t size) = 0;

    /**
     * Get how many bytes can be read without blocking.
     * @return The number of bytes can be read without blocking.
     */
    virtual int64_t available() = 0;

    /**
     * To move the file point to the given position.
     * @param pos the given position.
     */
    virtual void seek(int64_t pos) = 0;

    /**
     * To get the current file point position.
     * @return the position of current file point.
     */
    virtual int64_t tell() = 0;

    /**
     * Close the stream.
     */
    virtual void close() = 0;

    /**
     * Output a readable string of this input stream.
     */
    virtual std::string toString() = 0;
};

}
}
